Astron. Astrophys. 363, 517-525 (2000)

The effect of dust on photometric redshift measurement: a self-consistent technique ^*

B. Mobasher  ^{**  1} and P. Mazzei <sup>2

1</sup> Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA (mobasher@stsci.edu)
² Osservatorio Astronomico, Vicolo dell'Osservatorio 5, 35122 Padova, Italy (mazzei@pdmida.pd.astro.it)

Received 27 April 2000 / Accepted 26 July 2000

Abstract

A new method is developed for estimating photometric redshifts, using realistic template SEDs, extending over four decades in wavelength (i.e. from 0.05 to 1 mm). The template SEDs are constructed for four different spectral types of galaxies (elliptical, spiral, irregular and starburst), satisfying the following characteristics: a) they are normalised to produce the observed colours of galaxies at ; b) incorporate the chemo-photometric spectral evolution of galaxies of different types, in agreement with the observations; c) allow treatment of dust contribution and its evolution with redshift, consistent with the spectral evolution models; d) include absorption and re-emission of radiation by dust and hence, realistic estimates of the far-infrared radiation; e) include correction for inter-galactic absorption by Lyman continuum and Lyman forest. Using these template SEDs, the photometric redshifts are estimated to an accuracy of .

The simultaneous and self-consistent modelling of both the photometric and chemical evolution of galaxies and the effect of dust, makes this technique particularly useful for high redshift galaxies. The effects on the estimated photometric redshifts, due to assumptions in the evolutionary population synthesis models, are investigated and discussed. Also, the degeneracy in the predicted photometric redshifts and spectral types are examined, using a simulated galaxy catalogue.

Key words: galaxies: evolution galaxies: formation galaxies: photometry galaxies: starburst cosmology: observations

* Table 1 is only available in electronic form at the CDS via anonymous ftp to ftp://cdsarc.u-strasbg.fr//pub/cats/J/A+A/363/517 (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/363/517
** Affiliated to the Astrophysics Division of the European Space Agency

© European Southern Observatory (ESO) 2000

Online publication: December 11, 2000

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